Electronic devices formed in a cavity between substrates and including a via

ABSTRACT

An electronic device, such as a filter, includes a first substrate having a bottom surface and a top surface, a first side wall of a certain height being formed along a periphery of the bottom surface to surround an electronic circuit disposed on the bottom surface, an external electrode formed on the top surface, the external electrode being connected to the electronic circuit by a via communicating with the bottom surface and a second substrate. The second substrate has a second side wall of a certain height formed along a periphery of a top surface, the second side wall being aligned and bonded with the first side wall to internally form a cavity defined between the bottom surface of the first substrate, the top surface of the second substrate, the first side wall, and the second side wall.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to each ofU.S. Provisional Patent Application Ser. No. 62/429,218, titled “METHODSOF MANUFACTURING ELECTRONIC DEVICES FORMED IN A CAVITY HAVING REDUCEDINSERTION LOSS,” filed Dec. 2, 2016, U.S. Provisional Patent ApplicationSer. No. 62/429,223, titled “METHODS OF MANUFACTURING ELECTRONIC DEVICESTO PREVENT WATER INGRESS DURING MANUFACTURE,” filed Dec. 2, 2016, U.S.Provisional Patent Application Ser. No. 62/539,863, titled “METHODS OFMANUFACTURING ELECTRONIC DEVICES TO PREVENT WATER INGRESS DURINGMANUFACTURE,” filed Aug. 1, 2017, U.S. Provisional Patent ApplicationSer. No. 62/429,226, titled “METHODS OF MANUFACTURING ELECTRONIC DEVICESTO PREVENT DAMAGE DURING DICING,” filed Dec. 2, 2016, U.S. ProvisionalPatent Application Ser. No. 62/429,179, titled “METHODS OF MANUFACTURINGELECTRONIC DEVICES FORMED IN A CAVITY,” filed Dec. 2, 2016, U.S.Provisional Patent Application Ser. No. 62/539,861, titled “METHODS OFMANUFACTURING ELECTRONIC DEVICES FORMED IN A CAVITY,” filed Aug. 1,2017, U.S. Provisional Patent Application Ser. No. 62/429,183, titled“ELECTRONIC DEVICES FORMED IN A CAVITY BETWEEN SUBSTRATES,” filed Dec.2, 2016, U.S. Provisional Patent Application Ser. No. 62/429,186, titled“METHODS OF MANUFACTURING ELECTRONIC DEVICES FORMED IN A CAVITY ANDINCLUDING A VIA,” filed Dec. 2, 2016, U.S. Provisional PatentApplication Ser. No. 62/539,871, titled “METHODS OF MANUFACTURINGELECTRONIC DEVICES FORMED IN A CAVITY AND INCLUDING A VIA,” filed Aug.1, 2017, U.S. Provisional Patent Application Ser. No. 62/429,188, titled“ELECTRONIC DEVICES FORMED IN A CAVITY BETWEEN SUBSTRATES AND INCLUDINGA VIA,” filed Dec. 2, 2016, U.S. Provisional Patent Application Ser. No.62/539,873, titled “ELECTRONIC DEVICES FORMED IN A CAVITY BETWEENSUBSTRATES AND INCLUDING A VIA,” filed Aug. 1, 2017, and

U.S. Provisional Patent Application Ser. No. 62/429,190, titled“ELECTRONIC DEVICES FORMED IN A VACUUM SEALED CAVITY,” filed Dec. 2,2016. Each of these applications is incorporated herein by reference inits entirety for all purposes.

BACKGROUND

Conventionally, in a communication device such as a mobile phone, afilter device has been used to separate signals having different bandssuch as a transmission signal and a reception signal. An electronicdevice including a bulk acoustic wave (BAW) resonator such as a filmbulk acoustic resonator (FBAR) and a solidly mounted resonator (SMR) hasbeen used in the filter device. The electronic device includes a devicesubstrate on which an electronic circuit is disposed and a capsubstrate. The electronic device has been manufactured as follows:portions to be bonded between the device substrate and the cap substrateare formed with same type of metals such as gold or copper; the metalportions are covalently bonded with each other at high temperature andhigh pressure; and then the device substrate and the cap substrate arebonded together.

Background material describing FBAR filters and Surface Acoustic Wave(SAW) filters is described in “Development of FBAR Filters: InComparison with SAW Filters,” Transactions of Institute of Electronics,Information and Communication Engineers, Electronic Device, 103(728),9-14, Mar. 9, 2004.

SUMMARY OF INVENTION

Aspects and embodiments disclosed herein relate to electronic devices,such as filters, that are formed in a cavity between substrates andinclude a via, and methods of manufacturing same.

Some conventional methods of fabricating electronic devices includegold-gold bonding or copper-copper bonding that require a hightemperature and pressure process that may cause the device substrate,the cap substrate, and the like to be damaged and the manufacturingyield to be lowered. These conventional processes may include repeatedcycles between a normal temperature and pressure step and a hightemperature and pressure step, which may cause the cycle time to beunnecessarily elongated. Still further, in these conventional processesdefects may occur due to overetching in a process of forming athrough-hole, lowering the manufacturing yield.

Aspects of the present disclosure provide an electronic device and amethod of manufacturing the electronic device that may be used toimprove the yield, shorten the cycle time, prevent defects occurring dueto overetching in a process of forming a through-hole, or all of theabove.

A method of manufacturing an electronic device according to certainembodiments may include providing a first substrate having a first sidewall of a certain height formed along a periphery of a bottom surface ofthe first substrate, the first side wall surrounding an electroniccircuit disposed on the bottom surface, the first side wall being formedby a first metal layer made of a first metal, providing a secondsubstrate having a second side wall of a certain height formed along aperiphery on a top surface of the second substrate, the second side wallbeing formed by a second metal layer made of a second metal and a thirdmetal layer made of a third metal stacked sequentially, aligning thefirst substrate with the second substrate to internally define a cavitybetween the bottom surface of the first substrate, the top surface ofthe second substrate, the first side wall and the second side wall, thefirst side wall opposing and contacting the second side wall, andheating the first substrate and the second substrate to bond the firstside wall and the second side wall with each other, the first metallayer, the second metal layer, and the third metal layer being heated toform alloy layers by transient liquid phase bonding. The first substratemay be made of a piezoelectric body. The electronic circuit may includeat least one of a film bulk acoustic resonator, a bulk acoustic waveelement, and a surface acoustic wave element.

The third metal may have a melting point lower than that of the secondmetal. The third metal may be different from the second metal. Heatingthe first substrate and the second substrate may include melting thethird metal layer and forming a first alloy layer and a second alloylayer with the first metal layer and the second metal layer,respectively. The third metal layer may be consumed when the first alloylayer and the second alloy layer are formed.

The second side wall may have a height greater than that of the firstside wall. A starting temperature of alloy forming between the thirdmetal layer and the second metal layer may be lower than that of alloyforming between the third metal layer and the first metal layer. Theremay be no state where the first metal, the second metal, and the thirdmetal are melted together during the transient liquid phase bonding. Thefirst substrate may have a thickness different from that of the secondsubstrate.

The first metal may include gold (Au). The second metal may includecopper (Cu). The third metal may include at least one of tin (Sn) andindium (In).

According to certain embodiments, the method of manufacturing theelectronic device may further include providing a printed circuit board,the first substrate and the second substrate bonded with each other bythe first side wall and the second side wall being mounted on a topsurface of the printed circuit board, the top surface of the printedcircuit board on which the first substrate and the second substrate aremounted being covered and sealed by resin including fillers havingrespective certain diameters, the first side wall and the second sidewall being internally withdrawn from respective peripheries of the firstsubstrate and the second substrate by a certain distance that is half orless of an average diameter of the fillers.

According to certain embodiments, an electronic device may include afirst substrate having a first side wall of a certain height formedalong a periphery of a bottom surface of the first substrate, the firstside wall surrounding an electronic circuit disposed on the bottomsurface, and a second substrate having a second side wall of a certainheight formed along a periphery of a top surface of the secondsubstrate, the second side wall being aligned and bonded with the firstside wall such that the first side wall opposes and contacts the secondside wall to internally form a cavity defined between the bottom surfaceof the first substrate, the top surface of the second substrate, thefirst side wall and the second side wall, the first side wall beingbonded with the second side wall by transient liquid phase bonding.

According to certain embodiments, an electronic device may include afirst substrate having a bottom surface and a top surface, a first sidewall of a certain height being formed along a periphery of the bottomsurface to surround an electronic circuit disposed on the bottomsurface, an external electrode being formed on the top surface, theexternal electrode being connected to the electronic circuit by a viacommunicating with the bottom surface, and a second substrate having asecond side wall of a certain height formed along a periphery of a topsurface, the second side wall being aligned and bonded with the firstside wall to internally form a cavity defined between the bottom surfaceof the first substrate, the top surface of the second substrate, thefirst side wall and the second side wall.

The external electrode may be disposed directly above the via. The firstsubstrate may have a thickness less than that of the second substrate.The top surface of the first substrate may have a surface roughnessgreater than that of the bottom surface of the first substrate. The sidesurface of the via may have a surface roughness greater than that of thetop surface of the first substrate. The first substrate may have aportion defining the cavity that is thicker than a periphery portion.

According to certain embodiments, a method of manufacturing anelectronic device may include forming a first side wall of a certainheight along a periphery of a bottom surface of a first substrate havinga bottom surface and a top surface to surround an electronic circuitdisposed on the bottom surface, forming a via communicating between thebottom surface and the top surface, forming the via including stacking afirst stop layer and a second stop layer sequentially on a portion ofthe bottom surface of the first substrate corresponding to the via andetching the first substrate to form a through-hole corresponding to thevia, a rate of etching the first substrate being greater than that ofthe first stop layer and a rate of etching the first stop layer beinggreater than that of the second stop layer, forming a second side wallof a certain height along a periphery of a top surface of the secondsubstrate, and aligning and bonding the first side wall and the secondside wall to internally define a cavity between the bottom surface ofthe first substrate, the top surface of the second substrate, the firstside wall, and the second side wall.

An external electrode connected to the via may be disposed on the topsurface of the first substrate. The etching of the first substrate maybe performed by dry etching. The first stop layer may include at leastone of titanium (Ti) and chromium (Cr) and the second stop layer mayinclude gold (Au). The second stop layer may have a thickness greaterthan that of the first stop layer. The electronic circuit may include awiring pad and the first stop layer and the second stop layer may beformed to be extended over the wiring pad.

According to certain embodiments, a method of manufacturing anelectronic device may include providing a first substrate having abottom surface and a top surface, a first side wall of a certain heightbeing formed along a periphery of the bottom surface of the firstsubstrate to surround an electronic circuit disposed on the bottomsurface, a via being formed to communicate between the bottom surfaceand the top surface, a first column of a certain height having adiameter greater than that of the via being disposed directly under thevia on the bottom surface, the first side wall and the first columnbeing formed by a first metal layer made of first metal, providing asecond substrate having a top surface upon which a second side wall of acertain height is formed along a periphery of the top surface of thesecond substrate, a second column of a certain height being formed onthe top surface at a position corresponding to the first column formedon the bottom surface of the first substrate, the second side wall andthe second column being formed by a second metal layer made of secondmetal and a third metal layer made of third metal sequentially stacked,aligning the first side wall with the second side wall such that thefirst side wall opposes and contacts the second side wall to internallydefine a cavity between the bottom surface of the first substrate, thetop surface of the second substrate, the first side wall and the secondside wall, and the first column opposes and contacts the second column,and heating the first substrate and the second substrate such that thefirst column and the second column are melted and bonded with eachother, the first metal layer, the second metal layer, and the thirdmetal layer being heated and formed into alloy layers by transientliquid phase bonding.

In certain embodiments, an electronic device may include a firstsubstrate having a bottom surface and a top surface, a first side wallof a certain height being formed along a periphery of the bottom surfaceof the first substrate to surround an electronic circuit disposed on thebottom surface, a via being formed to communicate between the bottomsurface and the top surface, a first column of a certain height having adiameter greater than that of the via being disposed directly under thevia on the bottom surface, and a second substrate having a top surfaceupon which a second side wall of a certain height is formed along aperiphery of the top surface of the second substrate, a second column ofa certain height being formed on the top surface at a positioncorresponding to the first column formed on the bottom surface of thefirst substrate, the second side wall and the second column beingaligned and bonded with the first side wall and the first column suchthat the first side wall opposes and contacts the second side wall and acavity is internally defined between the bottom surface of the firstsubstrate, the top surface of the second substrate, the first side walland the second side wall, the first side wall and the first column beingbonded with the second side wall and the second column, respectively, bytransient liquid phase bonding.

The piezoelectric body may include at least one of lithium tantalate andlithium niobate. The via may include a through-hole formed by dryetching. An external electrode connected to the via may be furtherdisposed on the top surface of the first substrate. The first column mayhave a diameter greater than that of the second column. Anotherelectronic circuit may be disposed on the top surface of the secondsubstrate and the second side wall may be formed to surround the otherelectronic circuit. The second substrate may be made of a piezoelectricbody. The electronic circuit disposed on the top surface of the secondsubstrate may include at least one of a film bulk acoustic resonator, abulk acoustic wave element, and a surface acoustic wave element.

According to certain embodiments, an electronic device may include afirst substrate having a first side wall of a certain height formedalong a periphery of a bottom surface of the first substrate, the firstside wall surrounding an electronic circuit disposed on the bottomsurface, and a second substrate having a second side wall of a certainheight formed along a periphery of a top surface of the secondsubstrate, the second side wall being aligned and bonded with the firstside wall to internally define a cavity between the bottom surface ofthe first substrate, the top surface of the second substrate, the firstside wall, and the second side wall, the cavity including an atmospherehaving a pressure lower than one atmospheric pressure.

In certain embodiments, a method of manufacturing an electronic devicemay include providing a first substrate having a first side wall of acertain height formed along a periphery of a bottom surface of the firstsubstrate, the first side wall surrounding an electronic circuitdisposed on the bottom surface, providing a second substrate having asecond side wall of a certain height formed along a periphery of a flattop surface of the second substrate, aligning the first substrate withthe second substrate to internally define a cavity by the bottom surfaceof the first substrate, the top surface of the second substrate, thefirst side wall, and the second side wall, the first side wall opposingand contacting the second side wall, and heating the first substrate andthe second substrate for the first side wall and the second side wall tobe bonded with each other, the heating being performed under vacuum.

The degree of vacuum during the heating may be controlled by a controlvalve. The first substrate and the second substrate may be preheated ata temperature of 100° C. or less under atmospheric pressure prior to theheating.

According to certain embodiments, a method of manufacturing anelectronic device may include forming a first side wall of a certainheight along a periphery of a bottom surface of a first substrate havinga bottom surface and a top surface to surround an electronic circuitdisposed on the bottom surface, forming a via communicating between thebottom surface and the top surface and an external electrode on the topsurface, and aligning and bonding the first side wall and the secondside wall to internally define a cavity between the bottom surface ofthe first substrate, the top surface of the second substrate, the firstside wall, and the second side wall, the forming the via and theexternal electrode including forming a through-hole in the firstsubstrate corresponding to the via, forming a sputtered film on the topsurface of the first substrate, forming a pattern corresponding to theexternal electrode over the sputtered film by photolithography, andforming the via and the external electrode simultaneously by plating andfilling metal into the through-hole. A negative-type liquid resist canbe used for the photolithography.

According to certain embodiments, a method of manufacturing anelectronic device may be provided, the electronic device including afirst substrate having a first side wall of a certain height formedalong a periphery to surround an electronic circuit disposed on a bottomsurface of the first substrate, the first side wall being formed on abottom surface of a first wafer as the bottom surface of the firstsubstrate and a first sealing portion of a certain height being formedalong the periphery, and a second substrate having a second side wall ofa certain height formed along a periphery on a top surface of the secondsubstrate, the second side wall being aligned and bonded with the firstside wall to internally define a cavity between the bottom surface ofthe first substrate, the top surface of the second substrate, the firstside wall, and the second side wall. The method may include forming thefirst side wall on a bottom surface of a first wafer as the bottomsurface of the first substrate and forming a first sealing portion of acertain height along a periphery, forming the second side wall on a topsurface of a second wafer as the top surface of the second substrate andforming a second sealing portion of a certain height along theperiphery, and aligning and bonding the first wafer and the second waferwith each other to internally define a cavity between the bottom surfaceof the first wafer, the top surface of the second wafer, the firstsealing portion, and the second sealing portion, the first sealingportion and the first side wall being bonded with the second sealingportion and the second side wall, respectively, by transient liquidphase bonding.

The first wafer and the second wafer may be substantiallycircular-shaped, respectively. The method may further include trimmingouter edges of the first sealing portion and the second sealing portionin the first wafer and the second wafer. The trimming may allow thefirst sealing portion and/or the second sealing portion to be exposed onthe peripheries of the first wafer and the second wafer. The trimmingmay form, in the first wafer and the second wafer, a sealing portionhaving a certain angle with respect to the bottom surface of the firstwafer or the top surface of the second wafer. The top surface of thefirst wafer and the bottom surface of the second wafer may be ground tocertain depths, respectively. The electronic device may be formed bydicing the first wafer and the second wafer into pieces. The first sidewall and the second side wall as well as the first sealing portion andthe second sealing portion may respectively include a first alloy layerand a second alloy layer bonded by transient liquid phase bonding.

According to certain embodiments, a method of manufacturing anelectronic device is provided, the electronic device including a firstsubstrate having a first side wall of a certain height formed along aperiphery to surround an electronic circuit disposed on a bottom surfaceof the first substrate and a second substrate having a second side wallof a certain height formed along a periphery of a top surface of thesecond substrate, the second side wall being aligned and bonded bytransient liquid phase bonding with the first side wall to internallydefine a cavity between the bottom surface of the first substrate, thetop surface of the second substrate, the first side wall, and the secondside wall. The method may include forming the first side wall on abottom surface of a first wafer as the bottom surface of the firstsubstrate and forming a first sealing portion of a certain height alonga periphery, forming the second side wall on a top surface of a secondwafer as the top surface of the second substrate, and forming a secondsealing portion of a certain height along a periphery, aligning andbonding the first wafer and the second wafer with each other tointernally define a cavity between the bottom surface of the firstwafer, the top surface of the second wafer, the first sealing portion,and the second sealing portion, forming a sealing portion between thebottom surface of the first wafer and the top surface of the secondwafer along the peripheries of the first wafer and the second wafer bybonding the first sealing portion with the second sealing portion, andsuitably separating the first wafer and the second wafer in an insideregion defined by the sealing portion into pieces using plasma. Thesealing portion may be ring-shaped.

According to aspects and embodiments described herein, transient liquidphase bonding is used and no high temperature and pressure process maybe necessary to bond the device substrate and the cap substrate of anelectronic device with each other. Therefore, the cycle time formanufacturing an electronic device may be reduced. Furthermore, a defectoccurring due to overetching in a process of forming a through-hole canbe prevented and thus the yield can be improved.

According to certain embodiments, a method of manufacturing anelectronic device may include providing a first substrate having a firstside wall formed along a periphery of a bottom surface of the firstsubstrate, the first side wall surrounding an electronic circuitdisposed on the bottom surface of the first substrate, the first sidewall being formed of a first metal layer made of a first metal,providing a second substrate having a second side wall formed along aperiphery of a top surface of the second substrate, the second side wallbeing formed of a second metal layer made of a second metal and a thirdmetal layer made of a third metal sequentially stacked, the second metaland the third metal being different from each other and from the firstmetal, aligning the first substrate with the second substrate tointernally define a cavity between the bottom surface of the firstsubstrate, the top surface of the second substrate, the first side wall,and the second side wall, the first side wall opposing and contactingthe second side wall, and heating the first substrate and the secondsubstrate to bond the first side wall and the second side wall with eachother by transient liquid phase bonding, the third metal layer beingmelted to form a first alloy layer and a second alloy layer with thefirst metal layer and the second metal layer respectively.

According to certain embodiments, a method of manufacturing anelectronic device may include forming a first side wall along aperiphery of a bottom surface of a first substrate and surrounding anelectronic circuit disposed on the bottom surface of the firstsubstrate, forming a via communicating between the bottom surface of thefirst substrate and a top surface of the first substrate, forming thevia including stacking a first stop layer and a second stop layersequentially on a portion of the bottom surface of the first substratecorresponding to the via and etching the first substrate to form athrough-hole corresponding to the via, a rate of etching the firstsubstrate being greater than that of the first stop layer and a rate ofetching the first stop layer being greater than that of the second stoplayer, forming a second side wall along a periphery on a top surface ofa second substrate, and aligning and bonding the first side wall and thesecond side wall to internally define a cavity between the bottomsurface of the first substrate, the top surface of the second substrate,the first side wall, and the second side wall.

According to certain embodiments a method of manufacturing an electronicdevice including a first substrate having a first side wall formed alonga periphery of the first substrate and surrounding an electronic circuitdisposed on a bottom surface of the first substrate and a secondsubstrate having a second side wall formed along a periphery on a topsurface of the second substrate, the second side wall being aligned andbonded with the first side wall to internally define a cavity betweenthe bottom surface of the first substrate, the top surface of the secondsubstrate, the first side wall, and the second side wall may includeforming the first side wall on a bottom surface of a first wafer as thebottom surface of the first substrate and forming a first sealingportion about a periphery of the bottom surface of the first wafer,forming the second side wall on a top surface of a second wafer as thetop surface of the second substrate and forming a second sealing portionabout a periphery of the top surface of the second wafer and aligningand bonding the first wafer and the second wafer with each other tointernally define a cavity between the bottom surface of the firstwafer, the top surface of the second wafer, the first sealing portion,and the second sealing portion, the first sealing portion and the firstside wall being bonded with the second sealing portion and the secondside wall respectively by transient liquid phase bonding.

In accordance with certain embodiments, an electronic device may includea first substrate having a first side wall formed along a periphery of abottom surface of the first substrate and surrounding an electroniccircuit disposed on the bottom surface of the first substrate, anexternal electrode being formed on a top surface of the first substrate,the external electrode being connected to the electronic circuit by avia communicating with the bottom surface of the first substrate, and asecond substrate having a second side wall formed along a periphery of atop surface of the second substrate, the second side wall being alignedand bonded with the first side wall to internally define a cavitybetween the bottom surface of the first substrate, the top surface ofthe second substrate, the first side wall, and the second side wall, thefirst side wall including a first alloy of a first metal and a thirdmetal, the second side wall including a second alloy of a second metaland the third metal, the first metal being different from the secondmetal and from the third metal.

BRIEF DESCRIPTION OF DRAWINGS

Various aspects of at least one embodiment are discussed below withreference to the accompanying figures, which are not intended to bedrawn to scale. The figures are included to provide illustration and afurther understanding of the various aspects and embodiments, and areincorporated in and constitute a part of this specification, but are notintended as a definition of the limits of the invention. In the figures,each identical or nearly identical component that is illustrated invarious figures is represented by a like numeral. For purposes ofclarity, not every component may be labeled in every figure. In thefigures:

FIG. 1 is a cross-sectional view showing a schematic configuration of anelectronic device according to an embodiment;

FIG. 2 is a cross-sectional view showing a structure in which anelectronic device in accordance with embodiments described herein isimplemented on a printed circuit board;

FIG. 3 is a cross-sectional view showing an alignment between a firstsubstrate and a second substrate;

FIGS. 4A-4C are cross-sectional views illustrating a transient liquidphase bonding;

FIGS. 5A and 5B are phase diagrams of gold and tin (Au—Sn) and copperand tin (Cu—Sn), respectively;

FIGS. 6A and 6B are phase diagrams of gold and indium (Au—In) and copperand indium (Cu—In), respectively;

FIG. 7 is a partially enlarged cross-sectional view illustrating a stoplayer of a via in accordance with an embodiment;

FIGS. 8A-8C are partially enlarged cross-sectional views illustrating aconventional via;

FIG. 9 is a flow chart of a process to form a via and an externalelectrode in accordance with an embodiment;

FIG. 10 is a partially enlarged cross-sectional view illustrating astructure of conventional via and external electrode;

FIG. 11 is a flow chart of a process to form conventional via andexternal electrode;

FIGS. 12A and 12B illustrate a method of manufacturing an electronicdevice according to embodiments described herein;

FIGS. 13A and 13B are cross-sectional views showing edge trimmed firstand second wafers;

FIGS. 14A and 14B illustrate a method of manufacturing an electronicdevice according to embodiments described herein;

FIGS. 15A-15I are a first set of schematic views illustrating a seriesof steps of a method of manufacturing an electronic device;

FIGS. 16A-16E are a second set of schematic views illustrating a seriesof steps of a method of manufacturing an electronic device;

FIGS. 17A-17E are a third set of schematic views illustrating a seriesof steps of a method of manufacturing an electronic device;

FIGS. 18A-18G are a fourth set of schematic views illustrating a seriesof steps of a method of manufacturing an electronic device;

FIGS. 19A-19D are a fifth set of schematic views illustrating a seriesof steps of a method of manufacturing an electronic device;

FIG. 20 is a cross-sectional view showing a schematic configuration of afirst variation of an electronic device according to aspects of thepresent disclosure;

FIG. 21 is a cross-sectional view showing a structure in which anelectronic device of the first variation is implemented on a printedcircuit board;

FIG. 22 is a cross-sectional view showing an alignment between a firstsubstrate and a second substrate according to the first variation;

FIG. 23 is a cross-sectional view showing a schematic configuration of asecond variation of an electronic device according to aspects of thepresent disclosure;

FIG. 24 is a block diagram of one example of a packaged module includingfilter circuitry according to various embodiments;

FIG. 25 is a block diagram of one example of a front-end moduleincluding an antenna duplexer implemented using examples of the filtercircuitry according to certain embodiments; and

FIG. 26 is a block diagram of one example of a wireless device in whichexamples of the filter circuitry can be used according to variousembodiments.

DETAILED DESCRIPTION

It is to be appreciated that embodiments of the methods and apparatusesdiscussed herein are not limited in application to the details ofconstruction and the arrangement of components set forth in thefollowing description or illustrated in the accompanying drawings. Themethods and apparatuses are capable of implementation in otherembodiments and of being practiced or of being carried out in variousways. Examples of specific implementations are provided herein forillustrative purposes only and are not intended to be limiting. Also,the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use herein of“including,” “comprising,” “having,” “containing,” “involving,” andvariations thereof is meant to encompass the items listed thereafter andequivalents thereof as well as additional items. References to “or” maybe construed as inclusive so that any terms described using “or” mayindicate any of a single, more than one, and all of the described terms.Any references to front and back, left and right, top and bottom, upperand lower, and vertical and horizontal are intended for convenience ofdescription, not to limit the present systems and methods or theircomponents to any one positional or spatial orientation.

An electronic device and a method of manufacturing the same according toaspects of the present disclosure will be described below in detail withreference to the drawings. FIG. 1 is a cross-sectional view showing aschematic configuration of an electronic device according to anembodiment. FIG. 2 is a cross-sectional view showing a structure inwhich an electronic device in accordance with an embodiment isimplemented on a printed circuit board.

As shown in FIG. 1, according to an embodiment, an electronic device 100includes a first substrate 10 having a certain thickness and a secondsubstrate 20 having a certain thickness and opposing the first substrate10 with a certain gap. The first substrate 10 may be referred to as adevice substrate. A bottom surface 10 a of the first substrate 10opposes the second substrate 20 and is provided with an electroniccircuit 18 including a film bulk acoustic resonator (FBAR) 11. Thesecond substrate 20 may be referred to as a cap substrate. A side wall30 is formed to define a certain gap between a top surface 20 a of thesecond substrate 20 and a bottom surface 10 a of the first substrate 10.The bottom surface 10 a of the first substrate 10, the top surface 20 aof the second substrate 20, and the side wall 30 define a cavity 19, inwhich the electronic circuit 18 disposed on the bottom surface 10 a ofthe first substrate 10 is internally included.

Referring to FIG. 2 showing a structure 150 in which an electronicdevice 100 is implemented on a printed circuit board 110, the electronicdevice 100 of FIG. 1 is now disposed upside down on a top surface 110 aof the printed circuit board 110. A resin layer 120 is disposed on thetop surface 110 a of the printed circuit board 110 to cover theelectronic device 100. In the structure 150, the second substrate 20acts as a cap to support the resin layer 120 above the electronic device100 and protect the cavity 19.

In particular, the first substrate 10 is made of a piezoelectric bodysuch as aluminum nitride (AlN) and zinc oxide (ZnO). A plurality of filmbulk acoustic resonators 11 are formed by thin films of thepiezoelectric body on the bottom surface 10 a of the first substrate 10.The film bulk acoustic resonators 11 are suitably connected to eachother by wiring pads 12 to form an electronic circuit 18 such as afilter and a filter device. It is to be appreciated that, although theelectronic circuit 18 includes film bulk acoustic resonators 11, asurface acoustic wave (SAW) element or a bulk acoustic wave (BAW)element such as a solidly mounted resonator (SMR) can be used inaddition to or instead of the film bulk acoustic resonators 11.

The second substrate 20 is made of, for example, silicon or similarmaterial. The second substrate 20 is supported by the side wall 30 onthe first substrate 10 such that the bottom surface 10 a of the firstsubstrate 10 and the top surface 20 a of the second substrate 20 areseparated via a certain gap. The side wall 30 is formed to surround theelectronic circuit 18 disposed on the bottom surface 10 a of the firstsubstrate 10 and to extend along a periphery 10 d of the first substrate10 and a periphery 20 d of the second substrate 20. The side wall 30includes a first alloy layer 31 made of an alloy of gold (Au) and tin(Sn) and a second alloy layer 32 made of an alloy of tin (Sn) and copper(Cu) and stacked on the first alloy layer 31 between the bottom surface10 a of the first substrate 10 and the top surface 20 a of the secondsubstrate 20.

FIG. 3 is a cross-sectional view showing an alignment between the firstsubstrate 10 and the second substrate 20. The cross-sectional view showsa state prior to bonding the first substrate 10 with the secondsubstrate 20 by the side wall 30. A first side wall 33 is disposed onthe bottom surface 10 a of the first substrate 10 and along theperiphery 10 d thereof, whereas a second side wall 34 is disposed on thetop surface 20 a of the second substrate 20 and along the periphery 20 dthereof. The first side wall 33 has a certain height and is disposed tobe inwardly withdrawn from the periphery 10 d of the first substrate 10by a certain distance. The first side wall 33 is formed by a first metallayer 36 having a first thickness and made of gold (Au) as the firstmetal. The second side wall 34 has a certain height and is disposed tobe inwardly withdrawn from the periphery 20 d of the second substrate 20by a certain distance. The second side wall 34 is formed by a secondmetal layer 37 having a second thickness and made of copper (Cu) as thesecond metal and a third metal layer 38 having a third thickness andmade of tin (Sn) as the third metal, the third metal layer 38 beingstacked on the second metal layer 37. Here, a width of the first sidewall 33 is less than that of the second side wall 34.

The first substrate 10 is aligned with the second substrate 20 such thatthe bottom surface 10 a of the first substrate 10, the top surface 20 aof the second substrate 20, the first side wall 33, and the second sidewall 34 can internally define a cavity 19 and the first side wall 33 canoppose and contact the second side wall 34. Thus, the bottom surface ofthe first side wall 33 abuts onto the top surface of the second sidewall 34. According to an aspect of the present disclosure, the firstsubstrate 10 and the second substrate 20 are maintained in the alignedstate and heated such that the first side wall 33 and the second sidewall 34 are bonded with each other by transient liquid phase (TLP)bonding into a single side wall 30.

FIGS. 4A-4C are partially enlarged cross-sectional views illustratingthe TLP bonding. FIGS. 4A-4C specifically show a portion including thefirst side wall 33 and the second side wall 34 in the first substrate 10and the second substrate 20 shown in FIG. 3. FIG. 4A shows the firstsubstrate 10 and the second substrate 20 before the alignment. The firstmetal layer 36 having a first thickness and made of gold (Au) as thefirst metal is disposed on the bottom surface 10 a of the firstsubstrate 10 to form the first side wall 33. The second metal layer 37having a second thickness and made of copper (Cu) as the second metal isdisposed on the top surface 20 a of the second substrate 20 and thethird metal layer 38 having a third thickness and made of tin (Sn) asthe third metal is stacked on the second metal layer 37 to form thesecond side wall 34 therewith.

FIG. 4B shows the first substrate 10 and the second substrate 20 beingaligned with each other to allow the bottom surface of the first sidewall 33 to oppose and contact the top surface of the second side wall34. Thus, the bottom surface of the first side wall 33 abuts onto thetop surface of the second side wall 34.

According to an aspect of the present disclosure, the first side wall 33and the second side wall 34 are heated with the bottom surface of thefirst side wall 33 contacting the top surface of the second side wall 34as shown in FIG. 4B, and are thus bonded with each other by TLP bondingto form a side wall 30 consisting of a first alloy layer 31 and a secondalloy layer 32. This heating process is performed while the firstsubstrate 10 and the second substrate 20 are maintained in a lowpressure atmosphere at temperatures ranging from 240° C. to 260° C. overfive to ten minutes. The process produces a first alloy layer 31 made ofa first alloy of gold and tin, which originate from the gold as thefirst metal of the first metal layer 36 of the first side wall 33 andthe tin as the third metal of the third metal layer 38 of the secondside wall 34. The process also produces a second alloy layer 32 made ofa second alloy of copper and tin, which originate from the copper as thesecond metal of the second metal layer 37 and the tin as the third metalof the third metal layer 38 of the second side wall 34.

FIG. 4C shows a state of the first side wall 33 and the second side wall34 bonded with each other by TLP bonding. The first side wall 33 and thesecond side wall 34 are bonded by TLP bonding such that the first alloylayer 31 and the second alloy layer 32 are sequentially stacked betweenthe bottom surface 10 a of the first substrate 10 and the top surface 20a of the second substrate 20. The first alloy layer 31 is made of firstalloy of gold and tin, which originate from the gold as the first metalof the first metal layer 36 and the tin as the third metal of the thirdmetal layer 38. The second alloy layer 32 is made of a second alloy ofcopper and tin, which originate from the copper as the second metal ofthe second metal layer 37 and the tin as the third metal of the thirdmetal layer 38.

According to an aspect of the present disclosure, the third metal of thethird metal layer 38 forming the second side wall 34 has a melting pointlower than that of the second metal of the second metal layer 37. Infact, tin as the third metal has a melting point lower than that ofcopper as the second metal. As such, allowing the third metal to have amelting point lower than that of the second metal may bond the firstside wall 33 with the second side wall 34 at a lower temperature and fora shorter time. Here, the bonding at a lower temperature preventsmachining strain and the like internally accumulated in the firstsubstrate 10 and the second substrate 20 from becoming undesirably highsuch that the bonding can be stably performed. Furthermore, the bondingmay be performed for a shorter time to improve the productivity.

In addition, according to the present disclosure, the second metal ofthe second metal layer 37 is different from the third metal of the thirdmetal layer 38 in the second side wall 34. The second metal may becopper whereas the third metal may be tin. Thus, the second side wall 34is configured to be made of different metals such that the second metallayer 37 and the third metal layer 38 are made of a second metal and athird metal respectively, and accordingly the alloy formation startingtemperature and the alloy formation rate are different between thesecond metal layer 37 and the third metal layer 38. Consequently, thethird metal of the third metal layer 38 can be prevented from flowingout due to its melting point being lower than that of the second metalof the second metal layer 37.

Furthermore, according to aspects of the present disclosure, and asshown in FIGS. 4A and 4B, the width of the first side wall 33 formed bythe first metal layer 36 of gold as the first metal is configured to beless than that of the second side wall 34 formed by the second metallayer 37 of copper as the second metal and the third metal layer 38 oftin as the third metal. Accordingly, a lesser amount of expensive goldas the first metal may be used in the first metal layer 36 of the firstside wall 33 and the greater width of the second side wall 34 may ensurethe strength of the side wall 30.

FIGS. 5A and 5B are phase diagrams of gold and tin (Au—Sn) and copperand tin (Cu—Sn), respectively. As can be seen from the phase diagrams,gold as the first metal, copper as the second metal, and tin as thethird metal have different melting points and the melting point of tinas the third metal is the lowest of the three metals. Therefore, whenthe surrounding temperature increases due to the heating, the tin as thethird metal starts melting, forms a first alloy of gold-tin with thegold as the first metal, and then forms a second alloy of copper-tinwith the copper as the second metal.

The temperature T1 shown in FIG. 5A and the temperature T2 shown in FIG.5B indicate upper limits of temperatures expected during the heating. Inthe regions extending up to the temperatures T1 and T2 as upper limits,a melting point of the alloy having certain components is uniquelydetermined and accordingly the alloy formation can be easily controlled.Furthermore, as can be seen in FIGS. 5A and 5B, the alloy formationstarting temperatures or the alloy formation temperatures are differentbetween the first alloy of gold-tin (Au—Sn) and the second alloy ofcopper-tin (Cu—Sn). Therefore, the melting states of the substantiallybinary systems may be overlapped rather than the melting states of aternary system such that the alloy formation can be easily controlled.

As shown in FIG. 4C, the side wall 30 formed by TLP bonding includes thefirst alloy layer 31 and the second alloy layer 32 and accordingly thethird metal layer 38 made of tin as third metal has been consumed andincorporated into the first alloy layer 31 and the second alloy layer32. The side wall 30 that does not include tin as third metal having alower melting point now has a remelting temperature that may exceed 300°C. Therefore, the electronic device 100 including the side wall 30 maysatisfy a heat-resistant standard required when subject to reflow andimplementation.

As shown in FIG. 3, 4A, or 4B, the height of the second side wall 34 isconfigured to be greater than that of the first side wall 33. Thus, thetotal of a second thickness of the second metal layer 37 and a thirdthickness of the third metal layer 38 included in the second side wall34 is configured to be greater than a first thickness of the first metallayer 36 included in the first side wall 33. Furthermore, regarding thetemperatures when the alloy formation starts, tin as the third metal hasa lower melting point than copper or gold, and copper as the secondmetal of the second metal layer 37 forming the second side wall 34 has ahigher melting point than gold as first metal of the first metal layer36 forming the first side wall 33. Therefore, tin as the third metal ofthe third metal layer 38 having a lower melting point can, beforereaching the melting point, start the alloy formation with copper as thesecond metal of the second metal layer 37 having a greater thickness andforming the second side wall 34. In addition, configuring the thirdmetal layer 38 to have less thickness allows an amount of tin as thethird metal of the third metal layer 38 melting and laterally flowingduring the bonding to be controlled according to a suitable temperatureprofile of tin as the third metal reaching the melting point.

FIGS. 6A and 6B are phase diagrams of gold and indium (Au—In) and copperand indium (Cu—In) respectively. Although tin is illustrated as thethird metal of the third metal layer forming the second side wall 34 inthe embodiments shown in FIGS. 1 to 5, indium (In) can alternatively beused as the third metal. As can be seen from the phase diagrams of FIGS.6A and 6B, in the case where indium is used as the third metal, gold asthe first metal, copper as the second metal, and indium as the thirdmetal have different melting points, and the melting point of indium asthe third metal is the lowest. Therefore, when the surroundingtemperature increases due to the heating, the indium as the third metalmelts, forms a first alloy of gold-indium with the gold as the firstmetal, and then forms a second alloy of copper-indium with the copper asthe second metal.

In the case where indium is used as the third metal, the heating processis performed while the first substrate 10 and the second substrate 20are maintained in a low pressure atmosphere at temperatures ranging from170° C. to 200° C. over five to 10 minutes. The temperature T3 shown inFIG. 6A and the temperature T4 shown in FIG. 6B indicate upper limits oftemperatures expected during the heating. The case where indium is usedas the third metal of the third metal layer 38 is similar to embodimentswhere tin is used as third metal of the third metal layer 38, except forthe heated surrounding temperatures and the like.

According to an aspect of the present disclosure, the thickness of thefirst substrate 10 is different from that of the second substrate 20.For example, the thickness of the first substrate 10 may be greater thanthat of the second substrate 20 and also the thickness of the firstsubstrate 10 may be less than that of the second substrate 20. Thethickness of the first substrate 10 is different from that of the secondsubstrate 20 and, when the first side wall 33 and the second side wall34 are aligned and in contact with each other as shown in FIG. 3, thetemperature of the first metal layer 36 contacting the third metal layer38 is different from that of the second metal layer 37, on which thethird metal layer 38 is stacked, due to the difference in heatconduction. According to an aspect of the present disclosure, tin as thethird metal of the third metal layer 38 has distinct startingtemperatures of alloy forming respectively with gold as the first metalof the first metal layer 36 and copper as the second metal of the secondmetal layer 37, such that the difference between the startingtemperatures is greater than the temperature difference originating fromthe thickness difference between the first substrate 10 and the secondsubstrate 20. Therefore, the bonding can be made under no influence ofthe difference in thickness between the first substrate 10 and thesecond substrate 20.

In the structure 150 in which the electronic device 100 is implementedon the printed circuit board 110 as shown in FIG. 2, the resin layer 120includes fillers 121 each having a certain diameter. Here, for example,the resin layer 120 may be made of epoxy resin and the filler 121 may bemade of silica. According to an aspect of the present disclosure, thereis a relationship between a distance t defined by the side wall 30internally withdrawn from the periphery 10 d of the first substrate 10and the periphery 20 d of the second substrate 20 and a particlediameter d of the filler 121 as follows:

t≤(averaged d)/2.

Thus, the distance t defined by the side wall 30 internally withdrawnfrom the periphery 10 d of the first substrate 10 and the periphery 20 dof the second substrate 20 is no more than half of the average of theparticle diameters of the fillers 121 included in the resin layer 120.

According to an aspect of the present disclosure, if the distance tdefined by the side wall 30 internally withdrawn from the periphery 10 dof the first substrate 10 and the periphery 20 d of the second substrate20 satisfies the aforementioned relationship with the particle diameterd of the filler 121, then the filler 121 is prevented from penetratinginto the gap defined between the bottom surface 10 a of the firstsubstrate 10 and the top surface 20 a of the second substrate 20.Therefore, the gap is filled with the resin layer 120 of lower elasticmodulus rather than the filler 121 of higher elastic modulus, such thatheat cycle tolerance of the structure 150 in which the electronic device100 is implemented on the printed circuit board 110 can be improved.Furthermore, according to the present disclosure, the side wall 30 isinternally withdrawn from the periphery 10 d of the first substrate 10and the periphery 20 d of the second substrate 20 by a certain distancet, and thus the side wall 30 made of metal does not need to be cut in aprocess for dicing the first substrate 10 and the second substrate 20into pieces from the wafer, such that the dicing process can be easilyperformed. For example, the thickness of the dicing blade for cuttingthe wafer does not have to be configured to be greater, as it need notcut through the metal side wall 30.

As shown in FIG. 1, according to the present disclosure, the externalelectrode 40 is disposed on the top surface 10 b of the first substrate10 configured as a device substrate in the electronic device 100. Theexternal electrode 40 is connected to a wiring pad 12 of the electroniccircuit 18 disposed on the bottom surface 10 a of the first substrate 10by a via 42, which is formed in a through-hole 10 c (see FIG. 7) passingthrough the first substrate 10 between the top surface 10 b and thebottom surface 10 a. The external electrode 40 includes a via 42 and anexternal electrode layer 43 disposed on a top surface of the via 42.According to an aspect of the present disclosure, the via 42 is formednot only by the metal filled into the through-hole 10 c but alsointegrally with a metal layer formed to have a certain thickness in acertain region around the through-hole 10 c on the top surface 10 b.Here, the via 42 is formed by copper plating and the external electrodelayer 43 is formed by solder plating. The via 42 has a portion formed ona sputtered film 41 deposited for surface treatment.

According to an embodiment, the external electrode 40 is disposed on thefirst substrate 10 configured as a device substrate on which theelectronic circuit 18 is disposed. Furthermore, the external electrode40 is disposed directly above the through-hole 10 c (see FIG. 7) at thelevel of the top surface 10 b. Therefore, a wiring distance extendingfrom the electronic circuit 18 to the external electrode 40 can beconfigured to be short so that the number of connection points can bereduced. Accordingly, the characteristics of the electronic device suchas an insertion loss of the filtering can be improved.

Furthermore, in the structure 150 in which the electronic device 100 isimplemented on the printed circuit board 110 as shown in FIG. 2, theelectronic device 100 is connected to an electrode 111 by the externalelectrode 40 disposed on the top surface 10 b of the first substrate 10configured as device substrate. The electrode 111 is disposed on a topsurface 110 a of the printed circuit board 110. Therefore, the distancebetween the printed circuit board 110 and the first substrate 10, i.e.,the distance between the top surface 110 a of the printed circuit board110 and the top surface 10 b of the first substrate 10, can be minimizedsuch that the stress acting due to a difference in linear expansioncoefficient between the printed circuit board 110 and the firstsubstrate 10 or the second substrate 20 configured as cap substrate canbe reduced. Accordingly, it is possible to reduce a frequency variationduring a reliability test.

Furthermore, the electronic device according to the present disclosuremay be configured to have the first substrate 10 thinner than the secondsubstrate 20. According to an embodiment, the electronic circuit 18 isdisposed on the bottom surface 10 a of the first substrate configured asdevice substrate including the through-hole 10 c and the externalelectrode 40 such that the stress acting on the first substrate 10 afterimplementation as shown in FIG. 2 can be reduced. As a result, the firstsubstrate 10 can be configured to have a reduced thickness. The less thethickness of the first substrate 10 becomes, the less the aspect ratioof the through-hole 10 c becomes. Therefore, it is possible to reducethe stress originating from the difference in linear expansioncoefficient between the metal of the via 42 filled in the through-hole10 c and the first substrate 10 and thus, to improve heat cycletolerance.

In the electronic device 100 of the embodiment shown in FIG. 1, the topsurface 10 b of the first substrate 10 on which the external electrode40 is disposed is configured to be more roughened than the bottomsurface 10 a on which the electronic circuit 18 is disposed.Furthermore, a sputtered film 41 is deposited to ensure the adhesivenessbetween the external electrode 40 and the top surface 10 b of the firstsubstrate 10. Accordingly, because the top surface 10 b of the firstsubstrate 10 is configured as more roughened, the contact area with thesputtered film 41 can increase to improve the adhesive strength.

Furthermore, in the electronic device 100 of the present disclosure, theside surface of the through-hole 10 c formed in the first substrate 10is more roughened than the bottom surface 10 a of the first substrateupon which the electronic circuit 18 is disposed. The through-hole 10 cis filled with metal forming the via 42 and, because the side surface ofthe through-hole 10 c is configured as oblique, the film formationenergy is so dispersed that the adhesive strength may be lowered.According to the present disclosure, the sputtered film 41 is depositedon the roughened side surface of the through-hole 10 c to ensure theadhesive strength between the sputtered film 41 and the side surface ofthe through-hole 10 c similar to that between the sputtered film 41 andthe top surface 10 b.

In the electronic device 100 of the embodiment shown in FIG. 1, thefirst substrate 10 may have graded thickness such that a portionincluding the electronic circuit 18 and defining a cavity 19 is thickerthan a portion where the bottom surface 10 a of the first substrate 10is connected to the top surface 20 a of the second substrate 20 by theside wall 30. The graded thickness may allow the portion including theelectronic circuit 18 and defining the cavity 19 of the first substrate10 to tolerate the tensile stress generated during a substrate bendingtest and the like in the structure 150 in which the printed circuitboard 110 is implemented.

FIG. 7 is a partially enlarged cross-sectional view illustrating a stoplayer of a via. As shown in FIG. 1, in the electronic device 100, afirst stop layer 16 and a second stop layer 17 are sequentially stackedon the bottom surface 10 a of the first substrate 10 directly under thevia 42. Etching rates are different between the first substrate 10, thefirst stop layer 16 and the second stop layer. Specifically, the etchingrate of the first substrate 10 is greater than that of the first stoplayer 16 whereas that of the first stop layer 16 is greater than that ofthe second stop layer 17.

The electronic device 100 of the present disclosure is configured tohave the first stop layer 16 and the second stop layer 17 sequentiallystacked on the first substrate 10 directly under the via 42 and alsohave the etching rate of the first substrate 10 greater than that of thefirst stop layer 16 and that of the first stop layer 16 greater thanthat of the second stop layer 17 such that a notch generation due tooveretching during the formation of the through-hole 10 c at the bottomportion of the via 42, i.e., a portion where the side surface of thethrough-hole 10 c intersects with the bottom surface 10 a of the firstsubstrate 10, can be suppressed. This may allow the metal to be filledin the through-hole 10 c without any defects when the via 42 is formedand thus the yield and the reliability of the product to be improved.According to embodiments disclosed herein, the through-hole 10 c of thefirst substrate 10 may be formed by dry etching process. Uponconfiguring the etching rate of the first substrate 10 to be greaterthan that of the first stop layer 16 and the first stop layer 16 to begreater than the second stop layer 17, the dry etching may allow for awide variety of choices of the materials. In contrast, when thethrough-hole 10 c is formed by wet etching process, it would bedifficult to choose the materials for the etching rate of the firstsubstrate 10 being greater than that of the first stop layer 16 and thatof the first stop layer 16 being greater than that of the second stoplayer 17.

According to the present disclosure, titanium (Ti), chromium (Cr) andthe like are used for the first stop layer 16 and gold (Au) and the likeare used for the second stop layer 17. Using these kinds of metals, itis possible to achieve a relationship in which the etching rate of thefirst substrate 10 is greater than that of the first stop layer 16 andthat of the first stop layer 16 is greater than that of the second stoplayer 17 and therefore the notch generation can be suppressed at thebottom portion of the via 42.

According to an aspect of the present disclosure, the first stop layer16 made of titanium or chromium is provided to eliminate an adhesivelayer for adhering the second stop layer 17. Although such an adhesivelayer has been commonly used for adhering the surface with a film formedby vapor deposition or sputtering, the first stop layer 16 made oftitanium or chromium may function as the adhesive layer.

According to an aspect of the present disclosure, the first stop layer16 is thinner than the second stop layer 17. The reduced thickness ofthe first stop layer 16 may prevent in-plane etching conditions fromvarying due to the decrease of the etching rate when the first stoplayer 16 is etched. Thus, it is possible to ensure that the first stoplayer 16 can be totally removed from the bottom surface of thethrough-hole 10 c by the etching and there would be no first stop layer16 partially remaining. Furthermore, the increased thickness of thesecond stop layer 17 may ensure the strength of the second stop layer 17after the etching. When the etching is finished, there is only a thinnedsecond stop layer 17 remaining on the bottom surface of the through-hole10 c.

Although the first stop layer 16 and the second stop layer 17 aredisposed on the bottom surface 10 a of the first substrate 10 directlyunder the via 42 as shown in FIGS. 1 and 7, the first stop layer 16 andthe second stop layer 17 may be extended to cover the wiring pad 12 ofthe electronic circuit 18 disposed on the bottom surface 10 a of thefirst substrate 10. Furthermore, the first stop layer 16 and the secondstop layer 17 may be used as a substitution of the wiring pad 12 of theelectronic circuit 18. The first stop layer 16 and the second stop layer17 have a thickness greater than the wiring pad 12 and may lower thewiring resistance.

Therefore, the first stop layer 16 and the second stop layer 17 can beextended over the wiring pad 12 and used for the wiring pad 12 such thatthe insertion loss of the electronic device 100 can be lowered.

FIGS. 8A-8C are partially enlarged cross-sectional views illustrating aconventional via at the bottom of which no stop layer exists as acomparative example. As shown in FIG. 8A, the wiring pad 12 of theelectronic circuit 18 is extended to a location directly under the via42 and connected to the via 42 with no stop layer interposed. Accordingto such a conventional configuration as shown in FIG. 8B, when athrough-hole 10 c is formed in the first substrate 10 by etching, anotch 10 d may be generated due to overetching at a portion where theside surface of the through-hole 10 c intersects with the bottom surface10 a. As shown in FIG. 8C, when metal is to be filled into athrough-hole 10 c, which includes a notch 10 d created at the bottom, toform the via 42, the metal sometimes fails to enter a portion of thenotch 10 d and causes a defect of insufficient metal, which thus mayreduce the yield of electronic devices 100.

The electronic device 100 of the embodiment shown in FIG. 1 includes acolumn 50 formed between the bottom surface 10 a of the first substrate10 and the top surface 20 a of the second substrate 20 directly underthe via 42. The column 50 is configured to have a diameter greater thanthat of the via 42. The first stop layer 16 and the second stop layer 17are interposed between the bottom surface 10 a of the first substrate 10and the column 50. Similar to the side wall 30, the column 50 is formedby a first alloy layer 51 made of gold-tin alloy and a second alloylayer 52 made of tin-copper alloy sequentially stacked.

When the first substrate 10 and the second substrate 20 are aligned asshown in FIG. 3, a first column 53 is disposed on the bottom surface 10a of the first substrate 10 directly under the via 42 and a secondcolumn 54 is disposed on the top surface 20 a of the first substrate 10at a location corresponding to the first column 53. The first column 53is formed by a first metal layer 56 made of gold as the first metal andhaving a first thickness. The second column 54 is formed by a secondmetal layer 57 and a third metal layer 58 sequentially stacked. Thesecond metal layer 57 is made of copper as the second metal and has asecond thickness. The third metal layer 58 is made of tin as the thirdmetal and has a third thickness. Here, the first column 53 has adiameter greater than that of the second column 54.

As shown in FIG. 3, the first substrate 10 and the second substrate 20are aligned with each other such that the bottom surface 10 a of thefirst substrate 10, the top surface 20 a of the second substrate 20, thesecond side wall 34 and the first side wall 33 can internally define acavity 19. The first side wall 33 and the second side wall 34 oppose andcontact each other, while the first column 53 and the second column 54oppose and contact each other. Thus, the bottom surface of the firstcolumn 53 abuts onto the top surface of the second column 54. Accordingto an aspect of the present disclosure, the first substrate 10 and thesecond substrate 20 are maintained in the aligned state and heated suchthat the first side wall 33 and the second side wall 34 are bonded witheach other by transient liquid phase (TLP) bonding into a single sidewall 30 while the first column 53 and the second column 54 are alsobonded with each other by TLP bonding into a single column 50. The TLPbonding process applied to the first column 53 and the second column 54may be similar to that of the first side wall 33 and the second sidewall 34 shown in FIG. 4.

According to the structure 150 in which the electronic device 100 isimplemented on the printed circuit board 110 as shown in FIG. 2, a resinlayer 120 is interposed between the top surface 110 a of the printedcircuit board 110 and the electronic device 100. When a heat cycle testis performed to the structure 150, the resin layer 120 interposedbetween the printed circuit board 110 and the electronic device 100 mayexpand and contract to generate tensile stress against the via 42.According to the present disclosure, the column 50 having a diametergreater than that of the via 42 is disposed directly under the via 42.Therefore, a strength tolerant to the effect on the via 42 caused bysuch tensile stress and heat cycle can be ensured and the reliabilitycan be improved. For example, it is possible to prevent a disconnectiondue to metal fatigue between the via 42 and the first stop layer 16, thesecond stop layer 17, or the wiring pad 12.

Furthermore, according to the present disclosure, the first column 53formed by the first metal layer 56 made of gold as the first metal has adiameter greater than that of the second column 54 formed by the secondmetal layer 57 made of copper as the second metal and the third metallayer 58 made of tin as the third metal. The TLP bonding allows the tinas the third metal of the third metal layer 58 having a lower meltingpoint to wet and spread over the gold as the first metal of the firstmetal layer 56, such that the cross-section of the first alloy layer 51made of gold-tin alloy can be gently tapered. Therefore, it is possibleto prevent stress concentration onto a portion where the bottom surface10 a of the first substrate 10 intersects with the column 50 and thusthe reliability can be further improved.

Furthermore, according to aspects of the present disclosure, thethrough-hole 10 c can be formed in the first substrate 10 by laser. Asshown in FIG. 1, according to an embodiment, the column 50 is disposedon the bottom of the through-hole 10 c with the first stop layer 16 andthe second stop layer 17 interposed. Therefore, even if the first stoplayer 16 and the second stop layer 17 are heated from the bottom of thethrough-hole 10 c when the through-hole 10 c is formed by laser, theheat is rapidly dissipated through the column 50 connected directlyunder the first stop layer 16 and the second stop layer 17 and thus thefirst stop layer 16 and the second stop layer 17 are protected from theheat. Therefore, lithium tantalate, lithium niobate, sapphire, glass andthe like, which are difficult to be processed by wet etching or dryetching when the through-hole 10 c is formed, can be used as materialfor the first substrate 10 to be processed by laser.

As shown in FIG. 1, the electronic device 100 has a cavity 19 internallydefined by the bottom surface 10 a of the first substrate 10, the topsurface 20 a of the second substrate 20, and the side wall 30. Accordingto an aspect of the present disclosure, the cavity 19 is filled withnitrogen or air and maintained at a pressure lower than one atmospherein pressure. Maintaining the cavity 19 below one atmosphere in pressuremay reduce the air resistance acting when the film bulk acousticresonator 11 of the electronic circuit 18 oscillates within the cavity19 such that the Q factor can be ensured and better characteristics canbe achieved. According to an aspect of the present disclosure, the firstside wall 33 and the second side wall 34 are bonded by TLP bonding undervacuum while the first substrate 10 and the second substrate 20 are inthe aligned state as shown in FIG. 3. Therefore, even if the first sidewall 33 and the second side wall 34 are heated during the TLP bondingprocess, the gold as the first metal of the first metal layer 36 formingthe first side wall 33 as well as the copper as the second metal of thesecond metal layer 37 and the indium as the third metal of the thirdmetal layer 38 forming the second side wall 34 can be prevented fromoxidizing and nitriding. The prevention of oxidation may be advantageousto the TLP bonding of the present disclosure because, if the copper asthe second metal of the second metal layer 37 is oxidized, the secondalloy made of copper and tin may not be formed in the second alloy layer32 of the side wall 30 as shown in FIG. 1.

Still further, according to aspects of the present disclosure, the firstsubstrate 10 and the second substrate 20 aligned as shown in FIG. 3 maybe stored in a suitable chamber, which can be maintained at a suitabledegree of vacuum by a low-pressure control valve. Accordingly, theinside of the cavity 19 in the electronic device 100 can be set to asuitable degree of vacuum and thus the TLP bonding between the firstsubstrate 10 and the second substrate 20 can be reliably achieved. Yetstill further, a preheating process is performed at a temperature of100° C. or less prior to the TLP bonding between the first substrate 10and the second substrate 20 in the aligned state shown in FIG. 3A. Thepreheating process would not melt even the indium of a lower meltingpoint as the third metal of the third metal layer 38 forming the secondside wall 34 because the preheating temperature is set as 100° C. orless. In addition, the copper as the second metal of the second metallayer 37 in the second side wall 34 can also be prevented fromoxidation. Therefore, the formation of the second alloy made ofcopper-tin of the second alloy layer 32 of the side wall 30 as shown inFIG. 1 would not be inhibited.

As shown in FIG. 1, the electronic device 100 has the external electrode40 and the via 42 integrally formed with each other. The via 42 isintegrally formed not only by the metal filled into the through-hole 10c passing through the first substrate 10 between the top surface 10 band the bottom surface 10 a, but also by a metal layer formed to have acertain thickness on the top surface 10 b in a certain region around thethrough-hole 10 c. An external electrode layer 43 is disposed on the via42.

FIG. 9 is a flow chart showing a series of steps to form the via and theexternal electrode according to the present disclosure. At step 905, athrough-hole 10 c is formed to pass through the first substrate 10between the bottom surface 10 a and the top surface 10 b. Thethrough-hole 10 c may be formed for example by laser, dry etching, orwet etching. At step 910, a sputtered film 41 is formed on the topsurface 10 b of the first substrate 10 and the side surface of thethrough-hole 10 c. Here, the sputtered film 41 allows for an adhesion ofplated metal. At step 915, a negative-type liquid resist is used to forma resist pattern of the external electrode 40.

At step 920, copper is plated on the sputtered film 41. This allowscopper to be filled into the through-hole 10 c and also to be plated asmetal layer in a certain region around the through-hole 10 c on the topsurface 10 b of the first substrate 10 and a via 42 is formed.Furthermore, an external electrode layer 43 is formed by solder platingon the top surface of the via 42 to have a certain thickness. The via 42and the external electrode layer 43 constitutes the external electrode40. At step 925, the resist formed at step 915 is removed. At step 930,the sputtered film 41 is removed from the top surface 10 b of the firstsubstrate 10 except for the region where the external electrode 40 isformed.

According to an embodiment, the metal filled into the through-hole 10 cof the first substrate 10 and the metal layer formed in a certain regionaround the through-hole 10 c on the top surface 10 b of the firstsubstrate 10 to support the external electrode layer 43 are integrallyformed into the via 42. Therefore, the via 42 directly connects theexternal electrode layer 43 of the external electrode 40 disposed on thetop surface 10 b of the first substrate 10 with the first stop layer 16,the second stop layer 17, or the wiring pad 12 disposed on the bottomsurface 10 a of the first substrate 10 such that the connectionresistance and thus the insertion loss of the electronic device can belowered.

Furthermore, according to an aspect of the present disclosure,negative-type liquid resist is used for forming a pattern of theexternal electrode 40. Therefore, the external electrode 40 can bepatterned by preventing the resist from flowing into the through-hole 10c. The prevention can be achieved by controlling diameter and depth ofthe through-hole 10, volume of the via 42, viscosity of the resist,and/or pre-baking period of time for the resist.

FIG. 10 is a partially enlarged cross-sectional view illustrating astructure of a conventional via and external electrode as a comparativeexample. The conventional via includes a metal-filled portion 42 aformed in a through-hole 10 c of the first substrate 10 with a firstsputtered film 41 a interposed. The conventional external electrode 40includes an external electrode support layer 42 b and an externalelectrode layer 43. The external electrode support layer 42 b is formedon the top surface 10 b of the first substrate 10 with a secondsputtered film 41 b interposed. The external electrode layer 43 isformed on the external electrode support layer 42 b. Although themetal-filled portion 42 a of the conventional via and the externalelectrode support layer 42 b of the external electrode 40 are formed bycopper plating similar to the via 42 of the external electrode 40according to the previously described embodiments, what is different isthat the second sputtered film 41 b is interposed between themetal-filled portion 42 a and the external electrode support layer 42 b.

FIG. 11 is a flow chart showing a series of steps to form theconventional via and external electrode. At step 1105, a through-hole 10c is formed in the first substrate 10. At step 1110, a first sputteredfilm 41 a is formed by a first sputtering to cover a region includingthe side surface of the through-hole 10 c. At step 1115, a metal-filledportion 42 a is formed by copper plating on the first sputtered film 41a of the through-hole 10 c. At step 1120, the top surface 10 b of thefirst substrate 10 is polished to remove a copper plated portion and thefirst sputtered film 41 a formed on the top surface 10 b.

At step 1125, a second sputtered film 41 b is formed by a secondsputtering on the top surface 10 b of the first substrate 10 includingthe metal-filled portion 42 a. At step 1130, a resist pattern of theexternal electrode 40 is formed by photolithography. At step 1135, anexternal electrode support layer 42 b is formed by copper plating and anexternal electrode layer 43 is formed by solder plating. At step 1140,the resist is removed. At step 1145, the second sputtered film 41 b isremoved from the top surface 10 b of the first substrate 10 except for aportion where the external electrode 40 is formed.

According to the conventional via and external electrode 40 shown inFIG. 10 and the method of manufacturing the conventional via andexternal electrode 40 shown in FIG. 11, the metal-filled portion 42 aand the external electrode support layer 42 b are formed by separatesteps such that the second sputtered film 41 b is interposed between themetal-filled portion 42 a and the external electrode support layer 42 b.Thus, the number of steps increases and the connection resistancebetween the metal-filled portion 42 a and the external electrode layer43 increases due to the interposed second sputtered film 41 b.

With continuing reference to FIGS. 1 and 2, and with reference to FIGS.13A and 13B, FIGS. 12A and 12B illustrate a method of manufacturing anelectronic device according to the present disclosure. FIG. 12A shows astructure 200 including a first wafer 210 having a plurality of firstsubstrates 10 arranged to form the electronic device 100 and a secondwafer 220 having a plurality of second substrates 20 arranged to formthe same electronic device 100 such that the first wafer 210 and thesecond wafer 220 are aligned and bonded by TLP bonding with each other.In other words, FIG. 12A shows a state where the electronic device 100shown FIG. 1 has not yet to be diced into a piece from the first wafer210 and the second wafer 220 and the plurality of the electronic devices100 are coupled to each other.

FIG. 12B is a partially enlarged view of a boxed region R shown in FIG.12A that shows the structure 200 including substantially circular-shapedfirst and second wafer 210 and 220. As shown in FIGS. 12A and 12B, theportion where the configuration of the electronic device 100 is formedcorresponds to an effective area 201. A non-effective area 202, aring-shaped sealing portion 203, and a plating power supply portion 204having respective widths are sequentially formed outwardly from theeffective area 201 along a periphery 205.

According to the present disclosure, the sealing portion 203 isconfigured similar to the first side wall 33 disposed on the bottomsurface 10 a of the first substrate 10 and the second side wall 34disposed on the top surface 20 a of the second substrate 20. Thus, afirst sealing portion is formed along the periphery 205 on the bottomsurface of the first wafer 210 and a second sealing portion is formed onthe top surface of the second wafer 220 at a portion corresponding tothe first sealing portion. The first sealing portion includes a firstmetal layer made of gold as the first metal and having a firstthickness. The second sealing portion includes a second metal layer madeof copper as the second metal and having a second thickness and a thirdmetal layer made of tin as the third metal and having a third thickness,which are sequentially stacked.

When the first wafer 210 and the second wafer 220 are aligned with eachother and bonded by TLP bonding, the first side wall 33 and the secondside wall 34 are aligned to oppose and contact each other, while thefirst sealing portion and the second sealing portion are aligned tooppose and contact each other such that a cavity 19 is internallydefined by the first side wall 33 formed on the first wafer 210 and thesecond side wall 34 formed on the second wafer 220, similar to the casewhere the first substrate 10 and the second substrate 20 are aligned asshown in FIG. 3. Thus, the bottom surface of the first sealing portionabuts onto the top surface of the second sealing portion. The firstwafer 210 and the second wafer 220 are then heated in the aligned stateand the first side wall 33 and the second side wall 34 are bonded by TLPbonding to form a single side wall 30 while the first sealing portionand the second sealing portion are bonded by TLP bonding to form asingle sealing portion 203. The TLP bonding process of the first sealingportion and the second sealing portion is similar to that of the firstside wall 33 and the second side wall 34 as shown in FIGS. 4A-4C.

FIG. 13A is a cross-sectional view illustrating a state where thestructure 200 of the first wafer 210 and the second wafer 220 bondedwith each other is edge trimmed. As shown in FIG. 13A, the structure 200of the first wafer 210 and the second wafer 220 bonded with each otheris ground from the periphery 205 to a position where the ring-shapedsealing portion 203 is formed. Here, the sealing portion 203 isprocessed to ensure a length w1, for example, of 150 μm along the bottomsurface of the first wafer 210 or the top surface of the second wafer220. An inclined surface 251 processed by the grinding forms an angle θ,for example, of 60 degrees with respect to the bottom surface of thefirst wafer 210 or the top surface of the second wafer 220. Furthermore,the edge-trimmed inclined surface 251 is formed to a depth d3 from thetop surface of the second wafer 220 and a flange portion 255 is leftbeyond the depth d3. The depth d3 is, for example, 210 μm.

As shown in FIG. 13A, the first wafer 210 and the second wafer 220 arebonded into the structure 200, which is edge trimmed to form theinclined surface 251 and then the first wafer 210 is ground from the topsurface until a thickness d1 is achieved. The thickness d1 is 70 μm forexample. The second wafer 220 is ground from the bottom surface until athickness d2 is achieved. The thickness d2 is, for example, 110 μm.During this grinding process, the flange portion 255 is ground andremoved.

The manufacturing method described above allows the structure 200 havingthe first wafer 210 and the second wafer 220 bonded with each other tobe ground and edge trimmed from the periphery 205 to the ring-shapedsealing portion 203. Because the first wafer 210 and the second wafer220 are supported by the sealing portion 203, the first wafer 210 andthe second wafer 220 would not be broken when the first wafer 210 andthe second wafer 220 are ground to be thinner.

Furthermore, according to the manufacturing method described above, thestructure 200 having the first wafer 210 and the second wafer 220 bondedwith each other includes the inclined surface 251 formed by edgetrimming and having an angle θ, for example, 60 degrees, with respect tothe bottom surface of the first wafer 210 or the top surface of thesecond wafer 220. Because the sealing portion 203 is exposed on theinclined surface 251, a seed layer for plating can be depositedcontinuously from the periphery 205 to the center of the first wafer 210and the second wafer 220 along the inclined surface 251 with theresistance lowered.

Here, configuring the angle θ to be less than 90 degrees may allow theexposed area of the sealing portion 203 to be greater on the inclinedsurface 251 and may contribute to the lowered resistance. However, ifthe angle θ becomes too small, then the sealing portion 203 penetratesinto the wafer and narrows the effective area 201 such that the numberof the electronic devices to be diced out from the first wafer 210 andthe second wafer 220 may decrease. Consequently, to prevent thedecreased number of the diced electronic devices and ensure the loweredresistance of the seed layer for plating, the angle θ may be 60+/−20degrees or 60+/−10 degrees.

Furthermore, according to the manufacturing method described above, theinclined surface 251 formed by edge trimming includes the sealingportion 203. Therefore, the sealing portion 203 can block waterpenetration into the cavity defined by the bottom surface of the firstwafer 210 and the top surface of the second wafer 220 when the firstwafer 210 and the second wafer 220 are ground to be thinner or areexposed to a wet process. Still furthermore, when the bottom surface ofthe second wafer 220 is ground, the flange portion 255 formed along theperiphery 205 of the second wafer 220 can be simultaneously ground andremoved.

FIG. 13B is a cross-sectional view illustrating a state where thestructure 200 of the first wafer 210 and the second wafer 220 bondedwith each other is edge trimmed according to a conventionalmanufacturing method as a comparative example. The conventionalmanufacturing method grinds the first wafer 210 by edge trimming to forma vertical surface 253 having 90 degrees with respect to the bottomsurface of the first wafer 210 or the top surface of the second wafer220. The structure 200 of the first wafer 210 and the second wafer 220bonded with each other and edge trimmed includes no sealing portion 203between the bottom surface of the first wafer 210 and the top surface ofthe second wafer 220. Accordingly, the structure of the first wafer 210and the second wafer 220 bonded with each other may allow water topenetrate into a gap between the bottom surface of the first wafer 210and the top surface of the second wafer 220 when the top surface of thefirst wafer 210 or the bottom surface of the second wafer 220 is groundor exposed to a wet process.

FIGS. 14A and 14B illustrate a method of manufacturing an electronicdevice according to a further aspect of the present disclosure. As shownin FIG. 14A, the structure 200 of the first wafer 210 and the secondwafer 220 aligned and bonded with each other is adhered and secured ontoa rear-surface grinding protection tape 250. Here, the structure 200 isconfigured as shown in FIG. 12A. Specifically, the first wafer 210having a plurality of first substrates 10 arranged to form theelectronic device 100 and the second wafer 220 having a plurality ofsecond substrates 20 arranged to form the same electronic device 100 arealigned and bonded with each other. The first wafer 210 and the secondwafer 220 are bonded with a ring-shaped sealing portion 203 along theperiphery 205. The bonding may be performed by TLP bonding but anotheroption can be used to achieve a suitable bonding. For example, anorganic resin adhesive can be used.

According to the present disclosure, the structure 200 configured as thefirst wafer 210 and the second wafer 220 being bonded with the sealingportion 203 is diced into pieces into separated chips of the electronicdevices 100 using a plasma dicing-before-grinding (DBG) technique. Inparticular, an effective area 201 where the chips of the electronicdevice 100 are formed in the structure 200 of the first wafer 210 andthe second wafer 220 bonded with the sealing portion 203 is diced fromthe top surface of the first wafer 210 to a suitable depth by plasma.Then, the rear-surface grinding protection tape 250 is peeled away andanother rear-surface grinding protection tape is adhered onto the topsurface of the first wafer 210. Subsequently, the bottom surface of thesecond wafer 220 is ground to a suitable depth and the separated chipsare formed. The rear-surface grinding protection tape is peeled awayfrom the top surface to separate the structure 200 into pieces such thatthe electronic device 100 as a final product can be obtained.

According to an aspect of the present disclosure, the shapes of thefirst wafer 210 and the second wafer 220 can be maintained due to therigidity of the ring-shaped sealing portion 203 even after the bottomsurface of the second wafer 220 is ground. Therefore, the chips subjectto grinding resistance during the grinding process can be prevented frommoving such that the chips arranged adjacent to each other would notcause chipping and thus the chips of the electronic devices 100 can beseparated without damage. Consequently, the width between the adjacentchips to be diced can be narrowed to maximize the number of chipsobtained within the effective area 201.

FIG. 14B illustrates a conventional dicing process as comparativeexample. Conventionally, the structure 200 including the first wafer 210and the second wafer 220 that are not secured by the sealing portion 203along the periphery 205 is adhered onto the rear-surface grindingprotection tape 250 and then the chips of the electronic devices 100 arediced out from the effective area 201. The wafer has been thinned bymechanical grinding and dicing techniques using a diamond wheel. Suchconventional mechanical grinding and dicing techniques may causechipping, chip cracking, and wafer cracking such that the yield and theproductivity may be lowered.

FIGS. 15A through 15I illustrate a series of steps of a method ofmanufacturing an electronic device according to aspects of the presentdisclosure. As shown in FIG. 15A, a second wafer 220 is prepared and asputtered film 311 is formed on the top surface 220 a of the secondwafer 220. As shown in FIG. 15B, a resist 313 is applied by spin coatingonto the sputtered film 311 formed on the second wafer 220. As shown inFIG. 15C, the second wafer 220 having the resist 313 applied is subjectto exposure and a certain pattern is transferred. As shown in FIG. 15D,the exposed second wafer 220 is subject to post exposure bake (PEB) anddevelopment. Accordingly, a certain portion is removed from the resist313 and a recess 315 is formed. As shown in FIG. 15E, a copper plating317 is formed in the recess 315. As shown in FIG. 15F, the resist 313and the copper plating 317 are ground to have a flattened surface. Asshown in FIG. 15G, a tin plating 319 is applied onto the copper plating317. As shown in FIG. 15H, the resist 313 is removed. As shown in FIG.15I, the sputtered film 311 is further removed. As can be seen in FIG.15I, a second metal layer made of copper as the second metal and a thirdmetal layer made of tin as the third metal are sequentially stacked onthe top surface 220 a of the second wafer 220.

FIGS. 16A-16E illustrate a series of steps of a method of manufacturingan electronic device according to aspects of the present disclosuresubsequent to the steps of FIGS. 15A-15I. As shown in FIG. 16A, a firstwafer 210, which includes the film bulk acoustic resonator 325, the stoplayer 323, and the first metal layer 36 (See FIGS. 3, 4) made of gold asthe first metal suitably formed on the bottom surface 210 a, is preparedand aligned with the second wafer 220 shown in FIG. 15I. Then, thesecond and third metal layers sequentially stacked on the top surface220 a of the second wafer 220 is bonded by TLP bonding with the firstmetal layer formed on the bottom surface 210 a of the first wafer 210.Due to the bonding, a first alloy layer 321 made of gold-tin alloy and asecond alloy layer 322 made of copper-tin alloy are sequentially stackedbetween the bottom surface 210 a of the first wafer 210 and the topsurface 220 a of the second wafer 220. As shown in FIG. 16B, the firstwafer 210 is ground along its periphery such that an inclined surface327 on which the first alloy layer 321 and the second alloy layer 322are exposed. As shown in FIG. 16C, a rear-surface grinding protectiontape 329 is adhered onto the bottom surface 220 b of the second wafer220. As shown in FIG. 16D, the first wafer 210 is ground from the topsurface 210 b such that the first wafer 210 can have a certainthickness. As shown in FIG. 16E, the rear-surface grinding protectiontape 329 is peeled away from the bottom surface 220 b of the secondwafer 220.

FIGS. 17A-17E illustrate a series of steps of a method of manufacturingan electronic device according to aspects of the present disclosuresubsequent to the steps of FIGS. 16A-16E. As shown in FIG. 17A, a resist337 is applied by spin coating onto the top surface 210 b of the firstwafer 210. As shown in FIG. 17B, the first wafer 210 having the resist337 applied is subject to exposure and a certain pattern is transferred.As shown in FIG. 17C, the exposed first wafer 210 is subject to PEB anddevelopment. Accordingly, a certain portion is removed from the resist337 and a recess 339 is formed. As shown in FIG. 17D, dry etching isperformed through the recess 339 such that the first wafer 210 can beprocessed to have the top surface 210 b communicating with the bottomsurface 210 a until a through-hole 341 is formed to reach the stop layer323 formed on the bottom surface 210 a. As shown in FIG. 17E, the resist337 is removed.

FIGS. 18A through 18G illustrate a series of steps of a method ofmanufacturing an electronic device according to an aspect of the presentdisclosure subsequent to the steps of FIGS. 17A-17E. As shown in FIG.18A, a sputtered film 345 is formed to cover the top surface 210 b ofthe first wafer 210 and the side and bottom surfaces of the through-hole341. As shown in FIG. 18B, a resist 347 is applied by spin coating ontothe top surface 210 b of the first wafer 210 with the sputtered film 345interposed. As shown in FIG. 18C, the resist 347 disposed on the top ofthe through-hole 341 is removed by exposure, PEB and development and arecess 349 is formed. As shown in FIG. 18D, a copper plating 351 isformed in the through-hole 341 and the recess 349. As shown in FIG. 18E,a solder plating 353 is applied onto the copper plating 351. As shown inFIG. 18F, the resist 347 is removed. As shown in FIG. 18G, the sputteredfilm 345 is removed.

FIGS. 19A-19D illustrate a series of steps of a method of manufacturingan electronic device according to an aspect of the present disclosuresubsequent to the steps of FIGS. 18A-18G. As shown in FIG. 19A, thefirst wafer 210 and the second wafer 220 are reversed upside down and arear-surface grinding protection tape 357 is adhered onto the topsurface 210 b of the first wafer 210 that is now downside. As shown inFIG. 19B, the bottom surface 220 b of the second wafer 220 that is nowupside is ground until the second wafer 220 has a certain thickness. Asshown in FIG. 19C, the rear-surface grinding protection tape 357 ispeeled off from the top surface 210 b of the first wafer 210 that is nowdownside. As shown in FIG. 19D, the structure 200 is diced by plasma DBGinto separated chips of the electronic devices 100. Thus, the structure200 is diced from the top surface 210 b of the first wafer 210 to asuitable depth by plasma to form a gap 359. Subsequently, anotherrear-surface grinding protection tape is adhered onto the top surface210 b of the first wafer 210 and the bottom surface 220 b of the secondwafer 220 is ground to separate the chips of the electronic devices 100into pieces.

FIG. 20 is a cross-sectional view showing a first variation of anelectronic device according to a further aspect of the presentdisclosure. FIG. 21 is a cross-sectional view showing a structure inwhich an electronic device of the first variation is implemented on aprinted circuit board. The first variation in which the externalelectrode 40 is disposed on the bottom surface 20 b of the secondsubstrate 20 is different from the electronic device of the embodimentspreviously described in which the external electrode 40 is disposed onthe top surface 10 b of the first substrate 10 as shown in FIG. 1. Theother configurations of the first variation are similar to those of theelectronic device of the previously described embodiments.

FIG. 22 is a cross-sectional view showing an alignment between the firstsubstrate and the second substrate of the electronic device according tothe first variation. Also in the first variation, similar to theelectronic device shown in FIG. 3, the first substrate 10 is alignedwith the second substrate 20 such that the bottom surface 10 a of thefirst substrate 10, the top surface 20 a of the second substrate 20, thefirst side wall 33 and the second side wall 34 can internally define acavity 19 and the first side wall 33 can oppose and contact the secondside wall 34. The first substrate 10 and the second substrate 20 aremaintained in the aligned state and heated such that the first side wall33 and the second side wall 34 are bonded with each other by TLP bondinginto a single side wall 30.

The electronic circuit 18 illustrated in FIG. 1 and FIG. 2 that includesfilm bulk acoustic resonators 11 is disposed on the first substrate 10whereas the external electrode 40 is disposed on the second substrate 20in the electronic device of the first variation. Accordingly, theprocess of disposing the electronic circuit 18 on the first substrate 10can be separated from the process of disposing the external electrode 40on the second substrate 20 such that the respective substrates can beindividually processed. Therefore, the number of steps for each processmay be reduced and the processes can be easily performed on the firstsubstrate 10 and the second substrate 20.

FIG. 23 is a cross-sectional view showing a second variation of anelectronic device according to yet a further aspect of the presentdisclosure. In the second variation, an electronic circuit 28 includingfilm bulk acoustic resonators 21 is disposed also on the top surface 20a of the second substrate 20 as compared to the electronic device 100shown in FIG. 1. The electronic circuit 28 has the film bulk acousticresonator 21 suitably connected to each other by wiring pads 22 andconstitutes a filter, a filter device and the like with the electroniccircuit 18 disposed on the bottom surface 10 a of the first substrate10. According to the second variation, the electronic circuit 28 isdisposed also on the second substrate 20 such that the integrationdegree in the electronic device 100 can be improved to downsize theelectronic device 100 and achieve high functionality.

Embodiments of the filter circuitry 18 may be incorporated into andpackaged as a module that may ultimately be used in an electronicdevice, such as a wireless communications device, for example. FIG. 24is a block diagram illustrating one example of a module 2400 includingthe filter circuitry 18. The filter circuitry 18 may be implemented onone or more die(s) 100 including one or more connection pads, forexample, external electrodes 40 as illustrated in FIG. 1. For example,the filter circuitry 18 may include a connection pad 40 that correspondsto an input contact for the filter circuitry 18 and another connectionpad 40 that corresponds to an output contact for the filter circuitry18. The packaged module 2400 includes a packaging substrate, forexample, printed circuit board 110 as illustrated in FIG. 2 that isconfigured to receive a plurality of components, including the die 100.A plurality of connection pads, for example, electrodes 111 asillustrated in FIG. 2 can be disposed on the packaging substrate 110,and the various connection pads 40 of the filter circuitry 18 can beconnected to the electrodes 111 on the packaging substrate 110 to allowfor passing of various signals to and from the filter circuitry 18.Connection pads 40 and electrodes 111 are illustrated as overlapping inFIG. 24. The module 2400 may optionally further include other circuitrydie 2410, such as, for example, one or more additional filter(s),amplifiers, pre-filters, modulators, demodulators, down converters, andthe like, as would be known to one of skill in the art of semiconductorfabrication in view of the disclosure herein. In some embodiments, themodule 2400 can also include one or more packaging structures to, forexample, provide protection and facilitate easier handling of the module2400. Such a packaging structure can include an overmold formed over thepackaging substrate 110 and dimensioned to substantially encapsulate thevarious circuits and components thereon. The overmold may include, forexample, resin 120 as illustrated in FIG. 2.

As discussed above, various examples and embodiments of the filtercircuitry 18 can be used in a wide variety of electronic devices. Forexample, the filter circuitry 18 can be used in an antenna duplexer,which itself can be incorporated into a variety of electronic devices,such as RF front-end modules and communication devices.

Referring to FIG. 25, there is illustrated a block diagram of oneexample of a front-end module 2500, which may be used in an electronicdevice such as a wireless communications device (e.g., a mobile phone)for example. The front-end module 2500 includes an antenna duplexer 2510having a common node 2502, an input node 2504, and an output node 2506.An antenna 2610 is connected to the common node 2502.

The antenna duplexer 2510 may include one or more transmission filters2512 connected between the input node 2504 and the common node 2502, andone or more reception filters 2514 connected between the common node2502 and the output node 2506.

The passband(s) of the transmission filter(s) are different from thepassband(s) of the reception filters. Embodiments of the filter circuit18 may be included in the one or more transmission filters 2512 or theone or more reception filters 2514. An inductor or other matchingcomponent 2520 may be connected at the common node 2502.

The front-end module 2500 further includes a transmitter circuit 2532connected to the input node 2504 of the duplexer 2510 and a receivercircuit 2534 connected to the output node 2506 of the duplexer 2510. Thetransmitter circuit 2532 can generate signals for transmission via theantenna 2610, and the receiver circuit 2534 can receive and processsignals received via the antenna 2610. In some embodiments, the receiverand transmitter circuits are implemented as separate components, asshown in FIG. 25, however in other embodiments these components may beintegrated into a common transceiver circuit or module. As will beappreciated by those skilled in the art, the front-end module 2500 mayinclude other components that are not illustrated in FIG. 25 including,but not limited to, switches, electromagnetic couplers, amplifiers,processors, and the like.

FIG. 26 is a block diagram of one example of a wireless device 2600including the antenna duplexer 2510 shown in FIG. 25. The wirelessdevice 2600 can be a cellular phone, smart phone, tablet, modem,communication network or any other portable or non-portable deviceconfigured for voice or data communication. The wireless device 2600 canreceive and transmit signals from the antenna 2610. The wireless deviceincludes an embodiment of a front-end module 2500 similar to thatdiscussed above with reference to FIG. 25. The front-end module 2500includes the duplexer 2510, as discussed above. In the example shown inFIG. 26 the front-end module 2500 further includes an antenna switch2540, which can be configured to switch between different frequencybands or modes, such as transmit and receive modes, for example. In theexample illustrated in FIG. 26, the antenna switch 2540 is positionedbetween the duplexer 2510 and the antenna 2610; however, in otherexamples the duplexer 2510 can be positioned between the antenna switch2540 and the antenna 2610. In other examples the antenna switch 2540 andthe duplexer 2510 can be integrated into a single component.

The front-end module 2500 includes a transceiver 2530 that is configuredto generate signals for transmission or to process received signals. Thetransceiver 2530 can include the transmitter circuit 2532, which can beconnected to the input node 2504 of the duplexer 2510, and the receivercircuit 2534, which can be connected to the output node 2506 of theduplexer 2510, as shown in the example of FIG. 25.

Signals generated for transmission by the transmitter circuit 2532 arereceived by a power amplifier (PA) module 2550, which amplifies thegenerated signals from the transceiver 2530. The power amplifier module2550 can include one or more power amplifiers. The power amplifiermodule 2550 can be used to amplify a wide variety of RF or otherfrequency-band transmission signals. For example, the power amplifiermodule 2550 can receive an enable signal that can be used to pulse theoutput of the power amplifier to aid in transmitting a wireless localarea network (WLAN) signal or any other suitable pulsed signal. Thepower amplifier module 2550 can be configured to amplify any of avariety of types of signal, including, for example, a Global System forMobile (GSM) signal, a code division multiple access (CDMA) signal, aW-CDMA signal, a Long-Term Evolution (LTE) signal, or an EDGE signal. Incertain embodiments, the power amplifier module 2550 and associatedcomponents including switches and the like can be fabricated on galliumarsenide (GaAs) substrates using, for example, high-electron mobilitytransistors (pHEMT) or insulated-gate bipolar transistors (BiFET), or ona Silicon substrate using complementary metal-oxide semiconductor (CMOS)field effect transistors.

Still referring to FIG. 26, the front-end module 2500 may furtherinclude a low noise amplifier module 2560, which amplifies receivedsignals from the antenna 2610 and provides the amplified signals to thereceiver circuit 2534 of the transceiver 2530.

The wireless device 2600 of FIG. 26 further includes a power managementsub-system 2620 that is connected to the transceiver 2530 and managesthe power for the operation of the wireless device 2600. The powermanagement system 2620 can also control the operation of a basebandsub-system 2630 and various other components of the wireless device2600. The power management system 2620 can include, or can be connectedto, a battery (not shown) that supplies power for the various componentsof the wireless device 2600. The power management system 2620 canfurther include one or more processors or controllers that can controlthe transmission of signals, for example. In one embodiment, thebaseband sub-system 2630 is connected to a user interface 2640 tofacilitate various input and output of voice and/or data provided to andreceived from the user. The baseband sub-system 2630 can also beconnected to memory 2650 that is configured to store data and/orinstructions to facilitate the operation of the wireless device, and/orto provide storage of information for the user.

Having described above several aspects of at least one embodiment, it isto be appreciated various alterations, modifications, and improvementswill readily occur to those skilled in the art. Such alterations,modifications, and improvements are intended to be part of thisdisclosure and are intended to be within the scope of the invention. Itis to be appreciated that embodiments of the methods and apparatusesdiscussed herein are not limited in application to the details ofconstruction and the arrangement of components set forth in thedescription or illustrated in the accompanying drawings. The methods andapparatuses are capable of implementation in other embodiments and ofbeing practiced or of being carried out in various ways. Examples ofspecific implementations are provided herein for illustrative purposesonly and are not intended to be limiting. Also, the phraseology andterminology used herein is for the purpose of description and should notbe regarded as limiting. The use herein of “including,” “comprising,”“having,” “containing,” “involving,” and variations thereof is meant toencompass the items listed thereafter and equivalents thereof as well asadditional items. References to “or” may be construed as inclusive sothat any terms described using “or” may indicate any of a single, morethan one, and all of the described terms. Any references to front andback, left and right, top and bottom, upper and lower, and vertical andhorizontal are intended for convenience of description, not to limit thepresent systems and methods or their components to any one positional orspatial orientation Accordingly, the foregoing description and drawingsare by way of example only, and the scope of the invention should bedetermined from proper construction of the appended claims, and theirequivalents.

What is claimed is:
 1. An electronic device comprising: a firstsubstrate having a first side wall formed along a periphery of a bottomsurface of the first substrate and surrounding an electronic circuitdisposed on the bottom surface of the first substrate, an externalelectrode being formed on a top surface of the first substrate, theexternal electrode being connected to the electronic circuit by a viacommunicating with the bottom surface of the first substrate; and asecond substrate having a second side wall formed along a periphery of atop surface of the second substrate, the second side wall being alignedand bonded with the first side wall to internally define a cavitybetween the bottom surface of the first substrate, the top surface ofthe second substrate, the first side wall, and the second side wall, thefirst side wall including a first alloy of a first metal and a thirdmetal, the second side wall including a second alloy of a second metaland the third metal, the first metal being different from the secondmetal and from the third metal.
 2. The electronic device of claim 1wherein the first substrate includes a piezoelectric body.
 3. Theelectronic device of claim 1 wherein the electronic circuit includes atleast one of a film bulk acoustic resonator, a bulk acoustic waveelement, a solidly mounted resonator, and a surface acoustic waveelement.
 4. The electronic device of claim 1 wherein the externalelectrode is disposed directly above the via.
 5. The electronic deviceof claim 1 wherein the first substrate has a thickness less than athickness of the second substrate.
 6. The electronic device of claim 1wherein the top surface of the first substrate has a surface roughnessgreater than a surface roughness of the bottom surface of the firstsubstrate.
 7. The electronic device of claim 1 wherein a side surface ofthe via has a surface roughness greater than a surface roughness of thebottom surface of the first substrate.
 8. The electronic device of claim7 wherein the side surface of the via is covered in a sputtered film. 9.The electronic device of claim 1 wherein a portion of the firstsubstrate defining the cavity is thicker than a periphery portion of thefirst substrate.
 10. The electronic device of claim 1 wherein the firstside wall and the second side wall are bonded with each other bytransient liquid phase bonding.
 11. The electronic device of claim 1wherein the first metal includes gold.
 12. The electronic device ofclaim 11 wherein the second metal includes copper.
 13. The electronicdevice of claim 11 wherein the third metal includes one of tin andindium.
 14. The electronic device of claim 1 wherein the first side wallhas a width less than a width of the second side wall.
 15. Theelectronic device of claim 1 wherein the top surface of the firstsubstrate includes a sputtered film disposed beneath the externalelectrode.
 16. The electronic device of claim 1 wherein the externalelectrode comprises a first material layer including a portion passingthrough the via and an upwardly extending portion extending above thetop surface of the first substrate.
 17. The electronic device of claim16 wherein the external electrode further comprises a solder layerdisposed on an upper surface of the upwardly extending portion.
 18. Theelectronic device of claim 1 further comprising a first stop layerdisposed on a portion of the bottom surface of the first substrate atleast partially below the via.
 19. The electronic device of claim 18wherein the first stop layer includes at least one of titanium andchromium.
 20. The electronic device of claim 18 further comprising asecond stop layer disposed on the second stop layer at least partiallybelow the via.
 21. The electronic device of claim 20 wherein the secondstop layer includes gold.
 22. The electronic device of claim 1 furthercomprising a column disposed between the bottom surface of the firstsubstrate and the top surface of the second substrate below the via. 23.The electronic device of claim 22 wherein the column has a diametergreater than a diameter of the via.
 24. The electronic device of claim22 wherein the column includes a layer of the second alloy stacked on alayer of the first alloy.
 25. The electronic device of claim 24 whereina cross-section of the layer of the first alloy of the column istapered.
 26. The electronic device of claim 20 wherein the first stoplayer and the second stop layer are interposed between the bottom of thefirst substrate and the column.
 27. The electronic device of claim 1wherein a cross-section of the first side wall is tapered.